Automatic telephone system



.J. 6 3 1 s K w 1 July 19, 1927.

AUTOMATIC TELEPHONE SY STEM 2 Sheets-Sheet 1 Filed Sept. 10. 1921 -l Tiw-- John Hicks 2 I Z July 19, 1927. J WICKS AUTOMATIC TELEPHONE SYSTEM Filed Sept. 10, 1921 2 Sheets-Sheet 2 -'IfiEEntEf John MERE Z 4% Eng.-

Patented July 19, 1927.

I UNITED STATES,

PATENT O FFICE;

301m 'wIoxs, or CHICAGO, ILLINOIS, AssIGNoa; BY ivinsivn ASSIGNMENTS, ,TO AUTO- .MarIo ELECTRIC me, or CHICAGO, ILLINOIS, A CORPORATION o -DELAWARE;

AUTOMATIC TELEPHONE SYSTEM. I i

Application filed September 10, 1921. Serial No. 499,742.

The present invention relates in general to automatic telephone systems, and :has for its prinipal object the provision OfIlBW and improved circuits for selector and connector switches used insuch systems.

One of the objects of the invention is 'to provide .an improved circuit arrangement for a large capacityselector switch, that is, one-which has a plurality of setsoi wipers with a bank of contacts accessible to each set and which is capable of testing a plurality of trunk lines simultaneously.

Another object of the invention is to provide a large capacity rotary connector switch which is adapted to have access to trunk lines leading to private automatic exchanges "or to private branch exchanges which require a larger number of trunk lines than ten, this number :being ordinarily the largest group of trunks that can be given .to a branch exchange of this character without special provision. Heretofore, this situation was met by providing a connector switch which was capable of having an automatic vertical as well as a rotary selecting operation. The present case accomplishes the same result with only a rotary movement being-capable o-f testinga plurality of trunk lines simultaneously.

"The manner in which the-above and other results are accomplished will be described in detail hereina'fter with reference to the accompanying drawings.

In the drawings, comprising Figs. 1 and 2, there is shown by aneans of the usual circuit diagrams a connection between calling subscribers line and a trunk line extending to .a branch exchange. The apparatus involved in such a-connection is shown in the drawings and comprises a line switch C, seleo'tor D, and a rotary-connector H.

'Referringvnow to Fig. 1, there is-shown an automatic substation ,A of the usual type having associated with its line at the "exchange, the individual line or trunk selecting switch C The line switch is a switch off the well known rotary type whose wipers have no normal position always standing. in engagement when idle, with the trunk line last used. The line switch. C, in common with a plurality of other line switches, has access to trunk lines terminating in selectorv switches, one of [these trunk lines :being shown in the lector -D.

The selector D. is :a switch of the usual. Strowger vertical and rotary type. This selector =andithe other selectors of the group differ from the usual construction in that they are provided 'with an extra bank of drawing terminating in the secontacts andassociated wipers; Thus the selector D, whichhas twenty levels, has access to two hundred trunk lines, and .is.

is, it is adapted after selecting a group of trunk lines to select an'idle trunk line in the group, or if all the trunk lines in the group arebusy,'to return a busy signal to the calling'subscriber. Two of these trunk lines, one accessible to each set of wipers,

are shown in the drawings one of these indicated by the reference character vX, tor-- minating in the bunk contact set '167169,

inclusive, the other, indicated at Y, ter-.

minating in the contacts 173-175, inclusive.

\Vhile in the drawing there is only shown a first selector, thus, limiting the size of the exchange to a 3 digit'system, it will be appreciated that the capacity ofthe exchange may be increased: to any desired size by the addition of standard selector switches at the desired point int-he trunking system.

Having briefly described the apparatus I shown. in the drawings, adetailed description of its operation will now be given.

For this purpose" it will be assumed that the subscriber at substation A 'desires to extend In'order to do rthisthe subscriber at substation A will remove his receiver and -op-- crate his calling 'device' in accordance with the digits which constitute the number assigned to thexgroup change trunk lines.

jlVhen the receiver is removed at.substa a connection to a subscriber in a private 1 automatic exchange, two of the trunk lines extending to this :exchangerbeing shown in the drawings accessible to the connector of, private automatic exill tion A, a circuit is completed for the line relay 14 of the line switch C over the line conductors 11 and 12 in series. Relay 14, upon energizing, at its armature 23 completes a circuit which includes the winding of the switching relay 13 and the motor magnet 15 in series, and at its armature 22 connects the test wiper 26 to the above circuit at a mid point between the switching relay and the said motor magnet. The operation of the line switch C now depends upon whether its wipers 2527, inclusive, are associated with a busy trunk line or not. Assuming the associated trunk line to be busy, there will be a ground potential present upon the test contact engaged by the test wiper 26 and the motor magnet 15 being supplied with direct ground via the said test wiper will operate as a buzzer to advance the switch wipers step by step in search of an idle trunk line. However, it will be assumed in the present case that the wipers of the line switch are associated with an idle trunk line when the receiver is removed at substation A, and it will be assumed further that this trunk line is the one shown in the drawings terminating in the bank contacts 2830, inclusive. Under'these conditions, immediately following the energization of the line relay 14, the switching relay 13 energizes. Relay 13, upon operating, at its armature connects direct ground to the test contact 29 in order to prevent the selected trunk line being seized by another line switch, and at its armatures 19 and 21 disconnects the line conductors 11 and 12 from the winding of the line relay 14 and from ground, respectively, and extends them by way of wipers and 27, bank contacts 28 and 80, armatures 56 and 60 in selector D to the upper and lower windings of the line relay 33.

The line relay 33 is immediately energized over the calling subscribers line loop and, upon operating, at its armature 39 closes the circuit of the slow acting release relay 34. The latter relay, upon operating, at its armature prepares the operating circuits of the selector D and at its armature 43 places ground upon the release trunk conductor 44, thereby establishing a holding circuit for the line switch C. V

This circuit may be traced from ground on release trunk conductor 44, by way of test contact 29, test wiper 26 armature 20 and its front contact, through the winding of the switching relay 13, and thence through the winding of the motor magnet 15 to battery. It will be understood that this holding circuit is completed before the slow acting line relay 14 has had time to deenergize. A branch of this holding circuit also extends by way of the private normal conductor 16 to multiply connected test contacts in the banks of connector switches which have acnagnet, which deenergizes also.

with the dial tone machine T. By this means the calling subscriber is given an audible signal in order to notify him that he may now operate his calling device. hen the calling subscriber operates his calling device a series of interruptions is produced in the circuit of the line relay 33 in the selector D which deenergizes a plurality of times in response thereto. At each retraction of its armature 39 an impulse of current is sent over the following circuit: ground by way of back contact of armature 59, armature 39 and its back contact, armature 45 and its; front contact, through the winding of the slow acting relay 35, and thence through the winding of the vertical magnet 48 to battery. 48 operates toraise the two sets of switch wipers 7072, inclusive, and 73-75, inclusive, step by step until they are placed opposite the levels of bank contacts corresponding to the digit dialled. The slow acting relay 35 is energized in series with the vertical magnet and, upon the first-vertical movement of the switch when the oll -normal springs are operated, completes a circuit which extends from ground on release trunk conductor 44, front contact and armature 46, oilnormal spring 51 and its working contact, and through the winding of the stepping re lay 36 to battery. The relay 36 is energized over this circuit and, upon operating establishes a locking circuit for itself at armature and at armature 54 prepares the circuit of the rotary magnet. Another result of the energizationof the slow acting relay 35 is that a point in the circuit of the re lay 88 is opened at armature 47 in order to prevent the energization of this relay at this time. Shortly after the termination of the vertical movement otthe switch the slow acting relay 35 deenergizes and completes the circuit of the rotary magnet 52 at the normally closed springs controlled by armature 46. The rotary mag-v net operates to rotate the two sets of switch wipers into engagement with the first two sets of bank contacts in the two selected levels and at armature 53 opens the locking circuit of the stepping relay 36, which deenergizes, opening the circuit of the rotary The operation of the selector Dnow depends upon whether its first set of switch wipers -72, inclusive, is associated with a busytrunk line. there will be a ground potential present upon the test contact engaged by the test wiper 71 and a circuit will be completed which ex- The vertical magnet Assuming that this trunk line is busy,

IlL'r tends from the said grounded test contact,: by Way of test wiper 71 to junction;point ;69

where the circuit divides, one .path extending by way of the norn allyclosed springs controlled by armatureF-S, working contact of off-normal springs and-the saidspring, armature 47 and its back contact, and

through the winding of therelay 08 to battery,.-the other path extending byzway'of back contact and armature 66, armature 57 and its back contact, armature53 and its back contact, oft-normalspring 51 audits working contact, and through the wind ng 01' the steppmgrelay 36 to battery. Under the above conditions where a circuit is com; pleted simultaneously for the relays 3.6.and

If the trunk line associated withthe secondset of switch wi ers 7 3-7 5 incmsive, is bus ground will be connected to the test contact engaged by the test wiper 74 and the step ping relay 36will be energized from ground on the said test wiper. ,Relay 36,,upon operating, establishes a locking circuit for itself at armature and at armature 54 completes the circuit of the rotary magnet 52. Magnet 52 rotates the two sets. of switch wipers another step into engagement with the bank contacts associated with the next two trunk.

lines and at its armature 53 opens the 10.51; ing circuit of the stepping ,relay 36, which deenergizes, opening the circuit otthe rotary magnet, which deeuergizes. also.

the rotary magnet 52. will continue until one of the two sets of switchwipers of theselector D engages a set of bank contacts assoc1- ated with an idle trunk line, the wiper switching relay 38 being held energized until an idle trunk is found. It. will be assumed that the switch wipers 70.72, inclusive, are. the first set to engage the bank contactsassociated with an idle trunk line and it will. be further assumed that this the trunk. line shown in the drawings tern'linating in bank contacts 7880, inclusive. The wiper switching relay 38 will be deenergized .as there. will. be no ground,potential present upon the test contact engaged by. the .test wiper 71., and the switching relay 37, which has-been short circuited-during thertrunk selecting operation of the selector D, is energized in series with the stepping relay 36.. Relay 37, upon energizing, at armature 57 places ground upon the test contact 79 tllGYO-3 by busying the seized trunk lines so as to- It will The. alter nate operation of the stepping relay 36, and l t 1) b h fi tto be rotated preventit being connected. to byanothere selector switch, at-armature 58 opens a point 1n the clrcuit of the wiper switching relay 78 and 80, trunk conductors and 92,

,through the normally closed springsconw trolled. by armatures and 121, and'tothe upper and lower windingsof the'line relay 101 of the connector H.

The line relay [1010f the connector H is immediately energized over the calling line loop and, upon operating,- completes the circuit of. the slow acting relay 102. T he latter relay, upon energizing, at armature 127 prepares" certain-'impulsing circuit-s in the connector H-andat armature 126 placesground upon the-release trunk conductor 91 thereby establishing a, holding circuit for the sele ca tor D and the line switch C. v.This circuit may be traced from ground on release trunk 1 conductor" 91, bank contact 79, wiper 71, backcontact and armature'GG, armature 57' and its front contact, release trunk conductor I 1 44, restingcontact of cam spring 42 and the said spring, through the winding of the swithing relay37, armature and itsback contact, ofl-normalspring 51 and its work ing contact, and through the winding of the stepping relay 36 to'hattery. It will beun- .derstoodthat this holdingcircuit is completed before the. slow acting relay 34; has i had time to. retract its armatures. It will 1 be noted that this holding circuit applies ground to .;the release trunk conductor 4st whereby the line switch C is maintained in operated position.

Should the wipers 73-75, inclusive, of

intoengagement with the bank contacts asso- Yciated with-an idle trunk line the relay 38 will be maintained energized and the switch-,-

in 'rela 1 37'will o aerate. Under these con 1 a S .l

. ditions the operation of relay 37is effective to establish a locking c1rcu1.t,f or .wiper, switching relay 38 at armature 58, to place ground upon the test wiper 74; whereby the selected-trunk line is protected in the usual manner-,to open the circuit of theslow actline. I

Under certain conditions it night happen that all the trunks'in the selected level are busy." In'this case the relay '38 would be maintained energized and the relay 36 and the motor-magnet 52 would alternately open ate to cause the switch to test all the trunk lines in the level. When the switch shaft has been rotated eleven steps the switch wipers will no longer engage any bank contacts and the cam springs 41 and 42 will be operated. By this operation the circuit of the relay 37 is opened and a busy tone is given to the calling subscriber. The calling subscriber is in this manner notified that he must replace his receiver and again call his desired number. 7

Returning now to connector H, the description of the extension of the connection will now be proceeded with. WVhen the calling subscriber dials the next digit of his desired number, a series of interruptions is produced in the line circuit'of the line relay 101 and this relay retracts its armature a plurality of times in response thereto- At the first retraction of its armature 122 an impulse of current is sent over a circuit extending from ground by way of armature 122 and its back contact, armature 127 and its front contact, off-normal springs 144 and 130, through the winding of the slow acting relay 104, and thence through the winding of the vertical magnet 103 to battery. The above is the circuit over which the first vert-ical magnet impulse is sent. However, upon the first vertical step of the switch the off-normal springs are shifted and the remaining impulses to the vertical magnet traverse a new circuit, which is the same as the one previously traced, except that it includes the off-normal springs 144 and 139 and armature 128 and its front contact, relay 104 being now in an operated position. The vertical magnet 103 operates to raise the two sets of switch wipers 164166, inclusive, and 170172, inclusive, of the connector H step by step until they are placed opposite the two levels of bank contacts in which is lo cated the group of trunk lines extending to the desired private automatic exchange; The slow acting relay 104 is energized in series with the vertical magnet and maintains its armature attracted throughout the vertical operation of the switch and shortly after the termination thereof deenergizes and transfers the operating circuit to the rotary magnet 114.

The calling subscriber may now dial the next and final digit of his number. As be.

and thence through the winding of the rotary magnet 114 to battery. Magnet 114 operates to rotate the two sets of switch wipers into engagement with the first two trunk lines in the group extending to the desired private automatic exchange, which, we will assume, are the contact sets 167169, inclusive, and 17 3-17 5, inclusive. The slow acting relay 109 is energized in series with the rotary magnet at armature 145 short circuits the armature 141 and its back contact on the test relay so as toguard against premature opening of the rotary magnet circuit while the connector switch wipers are being rotated over busy trunk lines and at armature 146 completes a circuit of the slow acting relay 111. The latter relay, upon energizing, at armature 151 completes the circuit of the slow acting relay 110 and at armature 150 connects the test wiper 165 of the first set of wipers to the test relay 108. Relay 110, upon operating, at armature 147 prepares a point in the testing circuit of the test wiper 171 associated with the second set of wipers and at armature 149 Opens a point in the busy signalling circuit so as to prevent the calling subscriber getting a busy signal until all the trunks in the group are tested.

Assuming that the first trunk in the group is busy, which is the one engaged by the wipers 164-166, inclusive, ground will be connected to the test contact engaged by test wiper 165 and a circuit will be completed for the test relay 108. The latter relay, upon energizing, at its armature 142 prepares a point in the busy signalling circuit, at armature 141 opens a point in the circuit of the rotary magnet, at armature 140 prepares a point in the circuit of the lower winding of the switching relay 113, at armature 138 completes a test circuit for the test wiper 171 of the second set of wipers, and at armature 137 prepares a point in its locking circuit, which is closed im mediately upon the deenergization of the slow acting relay 111. If the second trunk of the group is busy there will be a ground potential present upon the test contact engaged by the test wiper 171 of the second set of wipers and the stepping relay 107 is energized over the following circuit: ground on the said test contact, by way of test wiper 171, armature 147 and its front contact, back contact and armature 148, front contact and armature 138, back contact and armature 136, and through the winding of the relay 107 to battery. Relay 107, upon energizing, at armature 135 establishes a locking circuit for itself and at, armature 134 completes the circuit of the rotary magnet 114. Magnet 114 operates to rotate the switch wipers into engagement,with the next two trunk lines in the selected group and at its armature 136 opens the locking circuit of the nected to the to stepping "relay 107 i which dcenergi zes; openingthe circuit oi" the rotary magnet, which deenergizes also. It will be seen that the SlOVV ilCiill relay 11* held energized in multiple th the re y magnet 114 and perates to maintain ie"test wiper 165 coniLze 108 and to hold the relay 1'10 energize l e next. two" trunk lines ai'e "busy the to relay 108 will be inaintaii L energized, .the stepping relay and the rotary magnet 1 145 are again operated to rotate the switch wipers into as; sociati onwith the nest twotrunk lines; The

alternate operation of the stepping relay- I07 and the rotary magnet-114 continue until one 'orthe other 0;": the two: sets of wipers are rotated into engagement with aset o'fbank contacts associated-witli an idjlc tiunk line.

(Sir

If the group of trunk lines selected is a "small group comprising an oddnuniber of trunk linesfit is necessary 'to stop the rotation of the connector H'as soon as all the trunk lines thegi oup have been tested. In order to do this there is no trunk line connected to the set of lija'nk contacts adapted to be engaged by thesecond set'ofli wipers 170-172, inclusive, on the last contact set' of the gronpi in this case when the connector is rotated The) engagement with this set of banlccontacts and the trunk line associated with'th'e set of'ccn tact engaged by the first,

set of switch wipers 16%166, inclusive is busy, the relay 108, is lield energized to prepare the circuit of ,tl1e'steppi 11g relay 107. 'i-isfthejcontact setasso'ciated with the second of wipers is dead it heing the last contactsetfof' tlie group, the 107 will nothe enei ed the rotation of the switch-c s." t will be noted that the slow ay 111 is wry mag} t and hence maintains its armature attracted the switch. The opertion of relay 111 serves? to inaintain'thetest wiper 165 con n'ecte-d with the test relay 1.08 during the rotation of the'connector also at armature 151 maintains the. circuit of the slow acting relay 110 closed. Shortly after the termination of the rotationlof the switch, the slow acting: relajiylll is'deener'gized and pens-the circuit of the slow acting; relay 110st armature and. atthe normally closed sprin controlled the armature 150 closes the locking circuit of the test relay 108-. As its circuit is open, the slow actin on relay :1'10 deenergizes' after ashort interval and at armature 147- prcpares noint in-the cii' of-the lowenwinding of switching. relP-J 1 3 and atv arniat-ure' 14 9 connects the lead from the busy'signaling' machine to. the lower heayy talking' eoncluctor wherebythe calling subscriber is given a busy tone in: the usual nannei Upon hearing-this signal the call ng subenerp i'zed ininultiple with during; the l rotation of scriber will? replace his receiver thereby initiat-ing the release of the operated switches in a manner WhlCltWillbG described here-- 'inafterp Should. tlierezbe an even number of} trunk lines in the selected group, the two contact sets adjacent tothe contacts associated with i the, preceding: trunk lines in the grou are left open and ground is connected perman 'ently to' the test contact ofthe contact set adapted to be engaged bythe first set of wipers. Theop erati on ofthe connector H wvhen it is rotated intof engagement with these two sets of contactsis similarfto that above described and will be perfectly apparent without further explanation."

We will nowzconsider the operationofthe connector- H When it is rotated into engage- .wipers are out ofeng'agementwith the bank contacts. the eleventh rotary position the cam spring123 is operated by aicam 12-1- on the switch shaftli As the: two sets of i switch wipers havebeen rotatedout oi enegag'ement with the bank contacts neither of the relays 108*01? l'OTwill'jbe energizedand therotary inagnetll l is. not operated By the operation of the cam 'spring l23. direct ground. is disconnected from the lower wind; ingof line relaylOI and ground throughythe secondary of the transformer of the busy machine is substituted .tlierefon. In this manner the usual audible. busy'signal isv returned to the cal'li'ng sub scriberr l The operation, of the connector HI Willi now be considered when thewswitch wipers are rotated into engagement with. the cont-a ct; set

associated with. an; idle trunk line in; the

selected group; In. the present ca se it will be assumed. that-the. relay 101 has operated to step they switch wipers into: engagement with an idle trunk line which, wefwill as sunie, is t'he I trunk line; tenminating: in bank contacts 1674169, inclusive. When this occursthere with be no ground potentiala'present, upon; the test contact 1 68: and: theicircuit of theftestre1ay-108 wihlberopenedf Then, I 1

following thei-deeneizgization of the slio w act?- ing relay 111, a circuit'is completed which extends firomf ground on release trunk con-' ductor 91, armature 137T and its back; con-- tact, armature 162-and its-back contact, lower winding oi the switching relay 112, back contact-and: armature 1 50, test wiper 165,

test contact 168, private normal conductor 194, through the winding of the switching relay 180 of the line switch C, and thence through the winding of the motor magnet 181 to battery. The switching relays 112 and 180 are energized over this circuit. However, due to a mechanical locking device controlled by the armature of the line relay 182 the switching relay. 180 in the line switch C is not fully operated at this time but only partiallyattracts its armatures, that is, enough to disconnect the selected trunk line from its normal battery and ground connections in the line switch O.

In the connector H, relay 112, upon .energizing, establishes a locking circuit for itseli at armature 154, places direct ground, upon the test contact 165 at armature 153, opens a points in the circuit of the test relay 108 at armature 155, at armature 156 opens a point in the circuit of the rotary magnet 114, and at armatures 152 and 157 connects ringing current to the selected trunk line. Ringing current is now intermittenly projected out over the called trunk line in order to operate a bridged rin'g down signal at the attendants cabinet in the private automatic exchange. Upon perceiving this signal, the attendant operator at the private automatic exchange will answer the call by inserting the plug of her cord circuit in the jack associated with the selected trunk line and operate the listening key in her cord circuit, or in any other suitable manner respond to the call. The subsequent operations wherein the connection completed to the desired private automatic exchange subscribers line takes place in the usual manner which, as it forms no part of the present invention need not be discussed herein. r

In the connector H, when the attendant operator answers the call the ring'cut oil relay 105 is immediately energized and, upon operating, establishes a locking circuit for itself at armature 132, at armatures 131 and 133 opens the ringing circuit and at the front contacts of these armatures finally completes the talking connection. The back bridge relay 100 is energized over the selected trunk line and at its. armatures 120 and 121 operates to reverse the battery in the calling line loop for metering or any other desirable purpose. Conversation may now be carried on between the calling subscriber and the branch exchange operator.

WVhen the conversation is terminated both the calling subscriber and the subscriber in the private automatic exchange will replace their receivers. In order to describe this releasing operation in detail it will be assumed that the calling subscriber replaces his receiver before the called subscriber. By this operation the circuit of the line relay 101 in the connector H is opened and this relay deenergizes thereby opening the circuit of the associated slow acting release relay 102. After the deenergization of the line relay 101 and before the deenergization of the slow acting relay 102, an impulse of current is sent to the slow acting relay 111 in series with the slow acting relay 109. The relay 111 is the only one operated .over this circuit as its winding is of such resistance that the low resistance relay 109 does not energize in series with it. Relay 111, upon energizing at armature 150 removes one ground connection from the release trunk conductor 91, and at armature 151 completes the circuit of the slow acting relay 110. The operation of relay 110 is without function when the switching relay 112 is the only one operated. However, when the switching relay 113 is operated the operation of 110 serves to remove one ground connection from the release trunk 91, in a manner similar to rela 111, at armature 1 17. Upon the deenergization of the slow acting relay 102, the previously traced circuit of the slow acting relay of 111 is opened at armature 127, and the ground is removed from the release trunk conductor 91 at armature 126. When ground is removed from the release trunk conductor,

91, the holding circuit of the switching relays 37 and 13 in the selector D and line switch C, respectively, are opened, thus allowing these relays to deenergize. Relay 37, upon deenergizing, restores certain circuits in the selector D to normal and at armature 59 completes the circuit of the release magnet 49. The magnet 49 operates to release the switch D. In the line switch C the deenergization of the switching relay 13 serves torestore the circuit connections in this switch to their normal position. In this manner the line switch 0 and the selector D are released.

In the connector H, the circuit of the slow actingrelay 111 being opened by the deenergization of the relay 102, this relay will deenergize opening the circuit of the slow acting relay 110. The deenergization of relay 111 serves to again apply ground to the release trunk conductor 91 over the following circuit; ground by way of armature 159 and its back contact, armature 153 and its front contact, armature 150 and its back contact, through the lower winding of the switching relay 112, back contact and armature 162, back contact and armature 137, to release trunk conductor 91. In this manner the-connector H is prevented from being seized by another selector switch while the called subscriber has his receiver off the switch hook.

hen the called subscriber replaces his receiver the back bridge relay 100 deenergizes and operates at armature 197 to open the locking circuit of the ring out ofl relay museum 105: and the switching relay 112,; and at armature 196 closes the: circuit of the release magnet 106; Magnet 106 operates-to restore the connector switch H to its normal position'."

i If the called subscriber replaces his re ceiver before the calling subscriber the back bridge 100 would be deenerg-ized' and the whole connection would be released upon the calling subscriber replacing his receiver upon the switch hook in a manner similar to that above described.

Returning now to the connector H its operation when the trunk line associated with the first set of switch wipers is busy and::thetrunk line associated with the second set of wipers is idle will now be considered. For this purposeit will be assumed that the connector switch has been irotatednntil' its wipers are associated .with the two trunk linesterminating in the contact "sets 167- 160, inclusive, and 173435, inclusive, As the tirst trunk line has been assumed to be busy the test rela y 108 will be held ener: gized and operate as before described. If the trunk line engaged by the second set of. wipers is idle the stepping relay 107 will not be energized andthe switch will not be iotatedp it will be remembered that the testrelay 108, upon operating, prepares a point in the circuit of the switching re'lay 113. Then, following the deenergization of the slow acting relays 111- and 110 a circuit is completed which extends fromground by way of front contact and armature 1450', lower winding oi the switching relay 113, back contact and armature 147, test wiper 171 test contact 174:, and thenceOVer the private normal conductor 195 through the winding of the switching relay and motor magn'etof the line switch which is associated with the seized trunk line to. battery. The switching relay in this line switch operates in the same manner as did the switching relay 180 in the line switch C to disconnect the trunk line from its normalbattery and ground connections.

In the connector H, relay 118, upon energizing, establishes a locking circuit for it self at armature 160, closes the circuit of the switching relay 112 at armature 161, at armature 159 disconnects ground from the armature 153 of the relay 112 and the front contact of this armature connects groundto the test contact 174% of the seizedtrunk line in order to busy it, and atarmatures 158 and 163 transfers the connection to the second: set of wipers thereby preparing the ringi circuit which is completed upon the ene': gization of relay 112. The subsequent operations wherein the connection isextendedto the desired calledlline, the conversation completed, and the release of connection takesfplace in a manner simllar to that before described The only difference in this i case is that as the switching relays 112 and 113 are energized, when the calling subscriber replaces his receiver before the called subscriber ground is replaced upon there.- leasetrunk after the preceding switches hawe been released through the lower windingrof the switching relay 113 by the deenergiza- 7 contacts 167-169, inclusive, has associated 1 with it the line switchC which is used on incoming calls fromfthe private automatic to main exchanges. It will of course be understood" that there is-aline switch. such C associated with each one of these two way trrrnl'c lines in the main. exchange; In order to briefly describe the operation of the line switch: (Yon an incoming} call" it will be assumed that a calling subscriber in the private automatic exchange desires to establish a connection with a subscriber in the main exchange, and it will be assumed further that this subscriber has extended the CODI18C' tion to the two way trunk line comprising conductors 190 and 191. When this occurs the line relay 1800f the line switch-C energized over the two trunk conductors series and the trunk selecting operationof this switch takes place in the usual manner.

The extension of the connection to thed'esired called line takes'place in a well known manner in accordance withthe digits dialled by the calling subscriber in the pri ate automatic exchange. The release of the connection is brought about by the calling subscriber replacing his receiver.

The features of the invention 1121 1 1119, been described and ascertained, what is considerec to be new and desired to have protected Letters Patent will be pointed out in the appended claims.

lVhatfI claim as my invention is: 7

1. In a telephone system, an automatic switch, two sets of wipers therefor, truni: lines accessible to each'set of wipers, "a test wiper in each of said sets, two test relays for said switch, one of-said sets of wipers normally in operative relation with said, switch, means for making any of said trunk lines busy, means'con'trollecl by said test wipers and said test relays for causing said switch to' select an idle one of said trunk lines, nieanscontro led by one of'said test relays operative at the beginning of said selecting operation for disconnecting said normally connected set of wipers and for transferring the other set of wipers into operati e relation withfsaid switch and for maintaining the said other set of wipers. in their trans ferredposition during said tr selecting operation and an operatingcircuit for; said last test relay including a wiper of the switch.

2. In a rotary Connector, two sets of wipers, sets of contacts arranged in groups and sub-groups accessible to each set of wipers, means for directively operating said connector in response to a series of impulses to advance both sets of wipers to corresponding groups, means for. directively operating said connector in response to a, second series of impulses to further advance both sets of wipers to subgroups in the selected groups, and means for then automatically advancing both sets of wipers over the contacts in the selected subgroups until one or the other of said sets of wipers arrives at an idle set of contacts. 7

3. In a rotary connector, two sets of wipers, sets of contacts arranged in groups and sub-groups accessible to each set of wipers, means for directively operating said connector in response to a series of impulses to advance both sets of wipers to corresponding groups, means for directively operating said connector in response to a second series of impulses to further advance both sets of wipers to sub-groups in the selected groups, means for then automatically advancing both sets of wipers over the contacts in the selected sub-groups until one or the other of said sets of wipers arrives at an idle set of contacts, two wiper switching relays, and means for connecting up the correct set of wipers by means of said relays.

4:. In a rotary connector, two sets of wipers, sets of contacts arranged in groups and sub-groups accessible to each set of wipers, means for directively operating said connector in response to a series of impulses to advance both sets of wipers to corresponding groups, means for directively operating said connector in response-to a second series of impulses to further advance both sets of wipers to sub-groups in the selected groups, means for then automatically advancing both sets of wipers over the contacts in the selected sub-groups until one or the other of said sets of wipers arrives at an idle set of contacts, two wipers switching relays, means for connecting up one set of wipers by energizing one relay alone, and means for connectingup the other set of wipers by energizing both relays together.

5. In a telephone system, a vertical and rotary connector switch having two sets of wipers, contact sets arranged in levels, one of said levels accessible to one of said sets of wipers, a second of said levels accessible to the other of said wipers, a group of trunk lines comprising runks terminating in the first half of said first and second levels, a second group of trunk lines comprising trunks terminating in the last half of said first and second levels, and means for operating said switch to select an idletrunk in said second group while one or more trunks of the first group are idle.

G. In a telephone system, a connector switch havingtwo sets of wipers, a group of contact sets accessible to one set of wipers, a second group of contact sets accessible to the other set of wipers, a group of trunk lines comprising trunks terminating in the first half. of each group of contact sets, a second group of trunk lines comprising trunks terminating in the last half of each group oi contact sets, automatic means for rotating said sets of wipers over said groups of trunk lines simultaneously, and automatic means for stopping said rotation at the end of each, group regardless oi the condition of the last set of trunks.

7. In a telephone system, a connector switch having two sets of wipers, a group of contact sets accessible to one set of wipers, a second group of contact sets accessible to the other set of wipers, two groups of trunk lines each i eluding trunk lines terminating in the first set of contact sets and other trunk lines terminating in the second grou of contact sets, and means for operating sai switch to select an idle trunk line in either group regardless of the busy or idle condition of the trunk lines in the other group.

S. A, rotary connector having two sets of wipers, means for directively advancing said wiper sets first in a primary movement and then in a secondary movement to select a group of trunks, and means for then automatically advancing said wiper sets until one or the other set arrives at an idle trunk.

9. In a telephone system, a rotary conector switch having directively controlled primary and secondary movements and automatic secondary movement, means for operating said switch in its several movements as set forth, two sets of wipers and two wiper switching relays for said switch, means for operatively connecting up one of said sets of wipers with said switch by energizing one of said switching relays alone, and means for operatively connecting up the other of said sets of wipe-rs with said switch by energizing both of said switching relays together.

10. In a telephone system, a rotary connector switch having means under directive control for giving the switch step by step primary and secondary movements, a plurality of sets of wipers for said switch, trunk line, accessible to each set of Wipers, means for automatically continuing the secondary movement to cause said switch to test consecutively a pair or said trunk lines at each step, and: means for operatively connecting up with said switch the first idle trunk line encountered by said Wipers in the testing operation.

11. In a. telephone system, an automatic switch, two groups of trunk lines accessible to said switch, each of said groups compris-' mg two sub-groups, means for making some trunk lines in both of said sub-groups busy, means for operating said switch into selective relation with the two sub-groups of one of said groups, and automatic means for then causing said switch to hunt for an idle trunk in both of said sub-groups, said means comprising two test wipers for said switch, two test relays for said switch, a circuit for one of said test relays independent of the other test relay and including one of said test wipers, and a circuit for the other test relay controlled by the first test relay and including the other test wiper of said switch.

12. In a rotary selector switch, two sets of wipers each including a test wiper, two test relays, a circuit including one test wiper for energizing and then holding up the first test relay while the switch is rotating, wiper switching contacts controlled by said first test relay, a circuit including the other test wiper for intermittently energizing the second test relay, a magnet for rotating the switch, and a circuit for said magnet controlled by the second test relay.

18. In a telephone system, an automatic switch, two sets of wipers therefor, trunk lines accessible to each set of wipers, one set of said wipers'normally in operative relation with said switch, means for positioning both sets of wipers on the first of a group of contact sets, a wiper switching relay for for disconnecting the normally connected set of wipers and for transferring the other set into operative relation with the switch, a stepping relay for controlling the subsequent movement of said wipers when both contact sets encountered are busy, circuits for both of said relays passing through a wiper of the normally connected wiper set in case the trunk associated with that set is busy and contacts on the first relay for preventing the operation of the second in case the trunk terminating in the contact set encountered by the normally disconnected wiper set is idle.

14. In a telephone system, an automatic switch, groups of lines accessible thereto, means for operating said switch to select one of said groups and a plurality of linesin said group, and means whereby said switch tests said selected lines consecutively and if found busy to cause said switch to automatically move to an adjacent plurality of lines of said group and to test said last mentioned lines simultaneously instead of consecutively.

15. In a telephone system, anautomatic switch of the two directional type, a plurality of wiper sets, a bank of contacts divided into a plurality of groups, lines terminating at said contacts, directive'controlled means for elevating one of said wiper sets opposite one group of said contacts and for simultaneously moving the other Wiper set opposite a second group of contracts, means for causing said switch to move both wiper sets to select an idle line of a group and automatic means effective after the directive movement for determining which wiper set will be used.

16. In a telephone system, an automatic switch of the two directional type, a plurality of wiper sets, a bank of contacts divided into a plurality of groups, lines terminating at said contacts, directive controlled JOHN WIGKS. 

